1. Field of the Invention
The present invention relates to a mounting structure of a thermal shield for an oil pump which is disposed, for example, in a motor vehicle.
2. Description of the Related Art
In general, an oil pump which is disposed in a motor vehicle or the like is used, for example, as a power source of a vehicular power steering device. This oil pump force-feeds hydraulic fluid to the device while being driven by an engine and causes hydraulic fluid to circulate through a system employing the power steering device. Protection needs to be provided for such an oil pump so as to prevent the temperature of hydraulic fluid in the system from rising, for example, due to radiant heat from a heat source such as an exhaust pipe. Thus, in order to prevent radiant heat from the heat source from being transmitted to the oil pump, the thermal shield is disposed between the oil pump and the heat source.
As the related art, there is shown in FIG. 10 a mounting structure of a thermal shield for an oil pump wherein a thermal shield 31 is mounted in the vicinity of an oil pump 32. The oil pump 32 is mounted to a cylinder block 35 while being sandwiched between a pair of brackets 33 (only one of the brackets 33 is shown in FIG. 10). A thermal shield 31, which is configured to cover a lateral surface of the oil pump 32, is securely mounted to an outer surface of the bracket 33 on the side of the heat source by means of more than two bolts 34, in such a manner that the thermal shield 31 is prevented from moving due to vibrations from the cylinder block 35. In this manner, the thermal shield 31 shields radiant heat from the heat source.
However, the related art wherein the thermal shield 31 is securely mounted at more than two points to the oil pump 32 or the bracket 33 is problematic in that the number of parts is great and that the cost for mounting the thermal shield 31 is high.
It is an object of the present invention to provide a mounting structure of a thermal shield for an oil pump which makes it possible to securely mount the thermal shield at one point with high reliability and at a low cost.
To solve the aforementioned problem, according to an aspect of the present invention, there is provided a mounting structure of a thermal shield for an oil pump, wherein the thermal shield which is disposed between the oil pump and a heat source and which prevents radiant heat from the heat source from being transmitted to the oil pump is mounted to a support portion, wherein the thermal shield is securely mounted at one point to the support portion, and wherein a fixture member disposed contiguous to the thermal shield and the thermal shield are provided with positioning portions and are engaged with each other to be positioned at the positioning portions.
In this construction, the thermal shield is mounted at one point to the support portion, and positioning portions of the fixture member and the thermal shield are engaged with each other to position the thermal shield. Thus, the number of required parts is small. As a result, the thermal shield can securely be mounted at one point to the support portion with high reliability and at a low cost.
In the aforementioned aspect of the present invention, the positioning portion of the fixture member and the positioning portion of the thermal shield may be engaged with each other with a pre-load being applied thereto by pre-load application means which is provided at one of the positioning portions.
In this construction, the positioning portion of the fixture member and the positioning portion of the thermal shield are engaged with each other with a pre-load being applied thereto by pre-load application means. Thus, the positioning portions of the thermal shield and the fixture member are integrated with each other. The thermal shield is inhibited from vibrating relative to the fixture member, for example, due to vibrations from the engine. As a result, the positioning portions are prevented from being disengaged from each other.
In the aforementioned aspect of the present invention, one of the positioning portions of the fixture member and the thermal shield may be a concave portion, and the other may be a protrusion portion which is engaged into the concave portion.
In this construction, the protrusion portion is surely engaged into the concave portion. Therefore, the thermal shield is prevented from rotating integrally when fixed at one point to the support portion.
In the aforementioned aspect of the present invention, the protrusion portion engaged into the concave portion may abut on a peripheral edge of the concave portion.
In this construction, the protrusion portion is in line contact with the concave portion. Therefore, it is possible to prevent chatter from being generated in the thermal shield, for example, due to vibrations from the engine.
In the aforementioned aspect of the present invention, the pre-load application means may be elasticity of the thermal shield itself.
In this construction, a pre-load is applied to the positioning portions due to the elasticity of the thermal shield itself. Therefore, it is possible to apply a pre-load to the thermal shield without increasing the number of parts.